#include <stdio.h>
#include <math.h>

#define PI 3.14

int main ()
{
	double r = 0;
	double v = 0;
	
	scanf("%lf",&r);
	v = (4.0/3)*PI*pow(r,3.0);
	printf("%.2lf",v);
	
	return 0; 
}
